The article starts of OK - reporting on the new WHO report on antibiotic resistance. But then it gets into the microbiome and what antibiotics supposedly do to it. Some quotes:

"But even more concerning, say experts like Dr. Martin Blaser, director of the human microbiome program at the New York University Langone Medical Center and author of Missing Microbes, is how these antibiotics are affecting the makeup of both good and bad bacteria that live within us – our microbiome. The first big cost of antibiotics is resistance,” he says. “But the other side of the coin is [the fact that] antibiotics are extinguishing our microbiome and changing human development.”

Extinguishing our microbiome? Really? The evidence simply does not support such a claim. I personally think antibiotics may be contributing to messing up the microbiome in many people and that this in turn might be contributing to the increase in a variety of human ailments (e.g., I mentioned this issue in my TED talk and many many times here and elsewhere). But "extinguishing"? Not even close. In fact, many of the published sutdies done so far suggest that the human microbiome is pretty resilient in response to antibiotics. Really serious overselling of the impact of antiobitcs by Blaser.

And "changing human development?" Not sure what the evidence for that is either. Most likely this refers to the role the microbiome plays in immune system development but I am not aware of strong evidence that antibiotics lead to changes in human devleopment.

They then quote Blaser again:

If I prescribe a heart medicine for a patient, that heart medicine is going to affect that patient,” says Blaser. “But if I prescribe an antibiotic, that antibiotic will affect the entire community to some degree. And the effect is cumulative.

Yes antibiotics can affect more than one person because microbes (and resistance) can spread. But "the effect is cumulative"? I do not think that has been shown.

Finally, Time (well, Alice Park, the author) states (in relation to limiting overuse of antibiotics)

That may also help to protect our microbiomes, which in turn could slow the appearance of chronic diseases such as obesity, cancer and allergies.

What? Now antibiotics cause obesity? And allergies? And cancer? Sure - there is good reason to think that antibiotic usage plays a role in obesity and allergies. The evidence is not yet completely overwhelming but it is certainly a reasonable notion. But how did cancer get thrown in here?

I note - as I assume many know - I think the microbiome is critical to many human functions and phenotypes. And screwing with it via excessive use of antibiotics seems like a very very bad idea. The precautionary principle says to me we should avoid any antimicrobials unless absolutely necessary. But do we really need to overstate what we know in order to effect change? Do we need to say things like "antibiotics are extinguishing our microbiome" which is simply untrue? I don't think we do. I think we can be more careful, not mislead people, and still have an impact. And thus, I am giving out today's "Overselling the microbiome" award to Time magazine and Martin Blaser.

Disturbed gut colonisation patterns have been associated with allergic disease, but whether microbial variation is the cause or effect of these diseases is still under investigation. We are far from understanding what constitutes a “healthy gut microbiome” that promotes tolerance. This remains a major limitation and might explain some of the inconsistency in human intervention studies with prebiotics and probiotics. Multidisciplinary integrative approaches with researchers working in networks, using harmonised outcomes and methodologies are needed to advance our understanding in this field.

Such data suggest that bona fide associations may exist between microbiota and obesity in humans, although causality remains to be addressed. Whether these associations will hold up to large-scale replication has yet to be determined. This situation is reminiscent of genetic association studies done in the pre-genome-wide association scan era, during which many candidate associations were found using sample sizes which at the time were considered large, but were rather small in retrospect [54]. Very few of these earlier associations have held up to replication in the modern era, where the threshold for association is more stringent and requires sample sizes orders of magnitude larger [55]. It seems reasonable to postulate that causal contributions from the gut microbiome to the development of human obesity have effect sizes on the order of common genetic variations implicated in complex diseases. If this is the case, much larger studies will be necessary before we have clear evidence of association.

This review considers the nature of the evidence supporting a relationship between the microbiota and the predisposition to disease as associative, correlative, or causal. Altogether, indirect or associative support currently dominates the evidence base, which now suggests that the intestinal microbiome can be linked to a growing number of over 25 diseases or syndromes. While only a handful of cause-and-effect studies have been performed, this form of evidence is increasing.

Talk by Rob Knight on "From Correlation to Causation in Human Microbiome Studies"

Update 5/4 #2. I would also recommend people check out the Helicobacter foundation web site. which has some useful background information on the organism and the diseases it causes.

A related question I have been thinking about involves Caesarian sections and whether they lead to an increased risk of any ailments that might have a microbial connection (e.g., obesity, allergy, autoimmune diseases). I started digging into the literature on this for my TED talk and then again when I posted something from the Smithsonian Genomics Exhibit that suggested there were no risks associated with C-sections.

Some papers on the topic suggest there may be some risks from C-sections related to these topics but that they are very very small:

And in at least a few of these stories, Martin Blaser's book is referenced in relation to whether antibiotic usage may contribute to this. So one might ask - is there evidence for whether antibiotics contribute to type 1 diabetes? I think the results are unclear and ambigious. See some of these papers and stories:

5 comments:

One of the most compelling reasons (and certainly not the only reason) to study the human microbiome is so that when we do have to use antibiotics, we can make sure that things return to a healthy stable state afterwards.

tl;dr : antibiotics not actually magic, have consequences which could maybe be mitigated if we were less ignorant.

Thanks for posting this, Jonathan! I've been seeing what seems to be a LOT of hype about this book, and have been hoping that the book itself is not quite so extreme ... I have not yet read the book myself - it's on my list of stuff to read soon.

The cancer reference is probably relating to Helicobacter pylori. Blaser has been concerned about the increase in of certain cancers (Barrett's esophagus, adenocarcinoma of the esophagus) as H. pylori infections decrease. (E.g., see Blaser, M.J. 2005. An Endangered Species in the Stomach. Sci Am. 292: 38-45.) I have used some of his articles in microbiology classes - had students read arguments for and against the elimination of H. pylori. The consensus of my students, after reviewing evidence, was that his arguments against eliminating H. pylori did not convince them. (This did prompt some really interesting discussions, though!)